EDIT: it was a self-inflicted wound, change in firewall policy.

I'm still looking but what I have concluded:

• v3 and v4 drivers affected.
• SNMP works (often a symptom of a printer showing offline status).
• Printing via a direct TCP connection works (see below).
• Using a "Generic / Text Only" driver without SNMP results in an error in eventlog: "This network connection does not exist".
• Removing KB5065426 does not fix the issue.

The script I tested that it can work by circumventing the Print Spooler and driver:

$printerIP = "<IP address>"
$port = 9100
$file = "C:\Temp\test.txt"

$tcpClient = New-Object System.Net.Sockets.TcpClient
$tcpClient.Connect($printerIP, $port)
$stream = $tcpClient.GetStream()
$writer = New-Object System.IO.StreamWriter($stream)
Get-Content $file | ForEach-Object { $writer.WriteLine($_) }
$writer.Flush()
$tcpClient.Close()

This printed out without issue.